My experience is with my LSG vertical offset. Heat rises so even though I can achieve relatively even temps across the grates with my tuning plates, I still will have higher temps on the higher racks. I make use of this when cooking ribs, etc on the lower racks and chicken on the higher ones. The cooker has six racks plus two hanging bars at the top for sausage (maybe hang a small whole pig). A LOT of cooking space. This is one major difference from that of a horizontal smoker of similar size.

It has amazing airflow so really hard to get stale smoke,etc. The fact that heat rises plus the two stacks help in this regard, i suppose.

Also less footprint for the cooking space if that is important to you. If it is well designed and built with at least 1/4" inch steel,etc, you will get great cooks out a good smoker regardless of whether it s horizontal or vertical.